Older adults with impaired hearing may have a faster rate of brain shrinkage
as they age, a new study suggests.
A number of studies have found that older people with hearing
loss tend to have a quicker decline in their memory and thinking skills,
compared to those with normal hearing.
you suffer from hearing loss?
"We've known that common, age-related hearing loss is associated with
cognitive [mental] decline. The question is, why?" said Dr Frank Lin, an
assistant professor at Johns Hopkins University in Baltimore, and the lead
researcher on the new study.
The findings, he said, offer one potential explanation: older adults with
hearing problems lose brain volume more quickly than their peers with normal
The precise reason is not clear, and the real-life impact is unknown. The
study did not test participants' actual mental ability.
But the "biggest question", Lin said, is whether treating hearing
impairment can slow changes in brain structure and, more importantly, delay dementia.
He and his colleagues are now planning a trial to test that idea.
The current findings are based on 126 adults aged 56 to 86 who underwent
yearly MRI scans to track brain-tissue changes for up to a decade. At the time
of the first scan, they also had a physical and a hearing test. Of
participants, 51 showed some degree of hearing loss – mostly the mild
variety where people have trouble hearing soft voices, for instance.
Lin's team found that older adults with hearing problems showed a faster
decline in brain volume over the years – especially in brain regions involved
in processing sound and speech.
The study, published online in the journal NeuroImage, cannot prove
that hearing loss directly causes brain-tissue loss. But the basic "use it
or lose it" principle may apply, according to Lin.
"The ear is no longer sending clear messages to the brain," he
said. Without that input, sound-processing brain regions may change in
A study is needed
What's more, Lin said, those brain areas have other jobs, too. Among other
things, they play a role in memory and processing information other than
A hearing expert not involved in the study said it's
"interesting", and raises the question of whether treating hearing
impairment can prevent brain-tissue loss or slow mental decline.
"But we need a study to test that, and that study has yet to be
done," said Dr Ian Storper, an otologist at Lenox Hill Hospital, in New
Even though researchers have found a link between hearing loss and mental
decline, Storper noted, "That doesn't prove causation." Both hearing
loss and brain-volume loss are common parts of ageing, and there are many other variables that may be
related to both, Storper added.
Lin's team did account for some other health factors – like whether people smoked,
or had high blood pressure
or diabetes. And there was still a connection between impaired hearing and
greater brain-volume loss.
Impacted ear wax
But Lin agreed that what's ultimately needed is a trial testing whether
hearing loss treatment slows mental decline.
"In the end," Lin said, "what everyone cares about is, what
can we do about it?"
There are, of course, already reasons to treat hearing loss, Storper said.
In some cases, treatment can be as easy as removing impacted ear wax, he noted.
But often, older adults need a hearing aid or assistive devices that make it
easier to hear in specific situations – while talking on the phone or watching
TV, for example.
According to the US National Institute on Ageing, almost one-third of
Americans aged 65 to 74 have at least mild hearing loss – as do nearly half of
those aged 75 and older.
If impaired hearing is one contributor to mental decline and dementia, Lin
said, and then treating it could have a big impact on public health.
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